Mobile communication devices have become widespread in metropolitan areas throughout the world. There are a variety of types of mobile communication devices, most of which are generally referred to as cell or cellular phones. There are a number of different well-known air interfaces and protocols used to provide communication service, and the advantages of each are promoted by service providers in the marketplace. However, of equal or more concern to the users are the size and weight of the mobile communication device. Therefore manufactures have continued to reduce both the size and weight of such devices. One of the largest and heaviest components in any mobile communication device is the battery. This presents a problem because, in addition to size and weight, users are also interested in operation time without having to recharge or change a battery, and while a larger battery permits longer operation time, it increases the effective size and weight of the mobile communication device. Some advances in battery technology have allowed for smaller batteries compared to earlier batteries of equal energy capacity. However the use of smaller batteries has largely been made possible by reducing the power consumption of the mobile communication device, thereby allowing use of a smaller battery for equal operation time.
The push for lower power consumption has led to many innovative approaches to designing mobile communication devices, and manufactures continue to seek ways to reduce power consumption. Such efforts have led to lower voltage semiconductor devices, integration of sub-circuits formerly implemented with discrete components into monolithic packages, and other circuit level advance. At the same time, control of the various circuits through software has led to many advances in reducing power consumption. However, one area that hasn't been as intensively investigated is the air interface. This is because the mobile communication device is required to comply with the air interface for events such as, for example, receiving incoming call page alerts. Page alerts are messages sent over a broadcast channel to alert a given mobile communication device that there is an incoming call. When the mobile communication device receives the page alert, it can alert the user of the mobile communication device accordingly, and the user can then commence communicating.
Because a page alert can occur randomly, the mobile communication device needs to regularly check for page alert and other messages. Typically the mobile communication device checks the air interface at regular intervals by receiving messages transmitted over a broadcast channel. If it receives a page alert with the appropriate identification information indicating an incoming call for the particular mobile communication device, the mobile communication device takes appropriate action to receive the call. However, the mobile communication device doesn't need to constantly receive information, and in fact doing so would substantially shorten the battery life due to the higher power consumption compared to an idle mode. Most mobile communication devices go into a low power mode typically referred to as a “sleep” mode when not actively receiving or transmitting, and periodically wake up to check the broadcast channel for incoming messages. The interval between these checks is fixed, and based on a worst case signal quality.
Even though the mobile communication device only periodically wakes up to check the broadcast messages, there is a still a significant amount of power consumption associated with this activity. Therefore there is a need to further reduce power consumption without significantly degrading the ability to receive incoming page alerts and other messages.